Since the time approximately 100 years ago when first technologies for wireless data transmission began to be employed, the bandwidth available for transmission has grown continuously. As is known, the width of the frequency band that can be used for transmission depends on the carrier frequency, so that as the frequency increases, the transmission bandwidths available also increase. Nowadays, carrier frequencies in the range from a few kilohertz to many gigahertz are used. Thus, so-called “wireless HD” operates with a carrier frequency of 60 GHz and bandwidths of 4 Gbit/s. In order to be able to achieve data rates in the range of 10 Gbit/s and higher, waves in the terahertz range will also be used as carriers in the future.
A problem in data transmission by means of such terahertz waves is that electronic circuits are limited to processing speeds below 100 GHz=0.1 THz on account of the lifetime of free electrons and holes, and thus do not come into consideration for processing such high frequencies in the aforementioned terahertz range. Instead, optical methods are known, which mostly employ frequency mixing in order to reach the terahertz range in question from the range of visible light. These methods are relatively complicated.